Wiring 133/230Y System

broadgage:

That is very rare in the UK, is this overseas ?

You may need larger conductor sizes to keep voltage drop down.

For a two wire 230 volt circuit, voltage drop will be same as a UK standard circuit. Earth loop impedance may require larger conductors, since only 133 volts is available to earth rather than 230 volts.

However during an earth fault, the potential touch voltage is reduced to about 65 volts, less dangerous than the 115 volts on a standard UK system.


Standard MCBs and fuses can be used, the voltages marked on these are MAXIMUM voltages, NOT the required voltage. MCBs must be true double pole devices, not single pole and neutral.


RCDs for 2 wire circuits can be standard types, as the voltage between live conductors is the same as a standard UK supply. RCDs must be true two pole and not single pole and neutral.


Switches for lamps and appliances should be double pole, to open both live conductors.


If UK type 13 amp plugs/sockets are to be used, then these should be on circuits of 16 amps or less. 

Thanks


Do I use 0.8 seconds instead of 0.4 for my disconnection time?


Regarding switches for lamps I can't see the need for switching both poles as you are only controling the light instead of using the switch as safety isolation.

Kelly Marie Angel:

I'm surprised this type of system still exists i would of thought unless its some sort of special laboratory or industrialsupply I think it will be due to be changed out soon

Why change what works, especially when dealing with simplicity? 

Kelly Marie Angel:

I'm surprised this type of system still exists i would of thought unless its some sort of special laboratory or industrialsupply I think it will be due to be changed out soon

Such systems are virtualy unknown in the UK, but still popular overseas.

Much of the Middle east uses 127/220 volts which is pretty much the same thing.

A few parts of Europe also used 127/220, now called 133/230 in the interests of harmonisation, but probably still nearer 127/220.

Mexico uses 127/220 in places.

The PTB in Saudi Arabia recently announced that 127/220 volt systems are not to be installed in new buildings, but a lot remains.

broadgage:

I would be inclined to "play it safe" and use 0.4 seconds dissconnection times. 


I would consider two pole switches to be best practice for lamps, In the real world light switches ARE used as the means of isolation when replacing lamps, even if that is not the intention. Do not fancy 133 volts to earth on the shell of an E27 lamp, nor on the exposed metallic parts of a lamp that has been broken.

I get what you are saying, but how is that different from a fixture with a non polarized schuko? 

broadgage:

A non polarised mains socket provides complete isolation by simply removing the plug from the socket.

A single pole light switch still leaves a dangerous voltage potentialy exposed to touch when turned off.

Only when dealing with an E-26  or E-27 socket. GU sockets and fixed LED lights do not present this hazard.